Implantation of multi-electrode arrays is becoming increasingly more prevalent within the neuroscience research community. Many of these studies have been influenced by the recent interest from the NIH and other agencies toward the development of sensory and motor prosthesis. The primary component for both types of prosthesis will be the development of multi-electrode systems, which are biocompatible, electrically and mechanically stable, and include a degree of flexibility in individual electrode juxtaposition. A motor prosthesis implant must record electrical activity from nearby neural elements, requiring a relatively passive electrode/tissue interface. A sensory prosthesis, however, must employ an electrode system, which can inject stimulus currents into the nervous system without damaging either nearby neural elements or the metal electrode. Both types of implants will require an electrode system that "floats" on the brain in order to minimize movement of the electrode tip, which can potentially damage nearby cells. Feedback from several neuroscience research groups have expressed the need for commercially available multi-electrode arrays that can penetrate into sub-cortical spaces sometimes extending 4 to 8 mm below the cortical surface. Other researchers have also suggested the need for electrode systems that will provide arrays with electrodes having different spacing and depths. There is also a relatively small, but growing, community of researchers, at this time, which must not only record from their electrode arrays but stimulate through them as well. A multielectrode system that is biocompatible, electrically and mechanically stable, and employs design features allowing flexibility in the geometric layout and length of the individual electrodes within the array is needed in order to satisfy the multiple applications demanded by neuroscience researchers. Recent advances in laser machining of thin ceramic substrates, application of ultra-fine line gold conductors to ceramic, fabrication of extremely flexible cables, and fine wire management techniques associated with juxtaposing metal microelectrodes within a few hundred microns of each other will provide the bases for the development of a "Floating Multi-electrode Array", FMA. The FMA will use pure indium as the core conductor and Parylene-C as the primary insulation material. It will be designed to allow later incorporation of a bi-directional telemetry chip, which can be incorporated on to the FMA for wireless stimulation and or recording. [unreadable] [unreadable] [unreadable]